Computers, servers, rack mounted systems and so on may be too hot, too noisy, and consume too much space. In servers, particularly in rack mounted systems, heat related problems continue to grow. Since the number of transistors in an integrated circuit continues to double approximately every eighteen months, ever more computing power is being crowded into ever smaller spaces. While chips have gotten smaller and more dense, both their power requirements and resulting heat production have increased. Furthermore, this additional heat is being produced in more confined spaces (e.g., rack mounted systems). Thus, not only are computers getting hotter but heat density (e.g., heat generated per volume of space) is increasing and escape routes for that heat continue to shrink and/or become blocked.
As has been described in many patents, published patent applications, advertisements, articles and so on, conventional heat sinks in conventional cooling designs simply cannot accommodate these increasing heat densities. Therefore, recent attempts to remove heat from a computer have included using larger heat sinks, retrofitting computers with heat pipes, soldering fans onto hot chips, integrating fans into heat sinks, and so on. But larger heats sinks use more space, in some cases an unacceptable amount of space. Also, larger heat sinks may still not provide enough cooling. Similarly, fans use power, consume space, and produce noise. Small fans configured to move enough air to provide significant cooling tend to be noisy. Also, there is a space-imposed limit as to how many heat sinks, fans, and so on that can be added to some computing configurations like 1 U form factor units. Additionally, paths for moving ambient air may be restricted. Thus, most conventional air-cooling solutions have not achieved desired cooling and have negatively impacted component density.
Therefore, some systems have taken a liquid cooled approach. Liquid cooled systems are becoming more popular because liquid can absorb and dissipate approximately one thousand times more heat than conventional air cooling systems. In one example, a facilities chilled liquid delivery system has been built into a rack mount. Other rack mounted systems have reserved several rack spaces for a two-phase liquid refrigerant based sub-cooling element that can provide chilled liquid to units in a rack. However, these sub-cooling elements are typically two-phase liquid refrigerant based and thus expensive, noisy, difficult to service, environmentally unfriendly, unintelligent, and generally not redundant. Furthermore, they have typically required rack mounted server components (e.g., 1 U form factor components) to be re-engineered to interface with the new rack design, its fluid connectors, and so on. Additionally, refrigerant based systems have experienced condensation problems in server systems, particularly rack mounted systems, and may have environmental concerns associated with leaking refrigerants. These refrigerant based systems typically include a compressor and have therefore required copper or other substantially rigid piping to convey chilled fluid from place to place at pressures at and above 100 psi (pounds per square inch). Rigid, high-pressure piping can constrain system design and thus limit ad-hoc cooling reconfigurations.
One example add-in liquid cooled system is configured to fit in a 5.25 inch drive bay. The portion of the system housed in the 5.25 inch bay provides cooled liquid to a cold plate that is soldered or clamped onto a component (e.g., processor) that a user wishes to cool. Another example add-in liquid cooled system is configured to occupy several shelves in a rack. The portion of the system housed in the shelves provides a chilled two-phase liquid refrigerant to rigid tubing that can be fixed to liquid cooled components like a cold plate soldered onto a processor. These rigid refrigerant based systems can typically be described as having an evaporate cold plate that includes an evaporative flow path for directing a refrigerant through the cold plate that is in heat exchange relation with the electronic components to be cooled. For at least the reasons described above, these systems may not provide adequate cooling solutions.